With three mountains ahead of them, a day of punishment was looming -- but the cyclists were barely on the road out of Pau when one of them was already suffering.

Sammy Sanchez came crashing down, banging his shoulder off the tarmac and lying there for quite some time before team-mates helped him to his feet. Naturally he got back on his bike. This was the Tour de France and he bloody well had to get back on his bike. But Sammy, as David Harmon said on Eurosport, was in "a world of pain."

They all were, by the time they hit the Col du Tourmalet at the end of this 174km stage.

But before they got to Tourmalet, with its 2,115-metre climb, they had to negotiate the Col de Marie-Blanque (1,035m) and then, some 60kms later, the Col du Soulor (1,474m). And it was a foul day of wind and rain so the descents on wet, serpentine roads were going to be treacherous too.

As the peloton laboured to the top of Soulor, most of them put their rain jackets on, knowing that their body temperatures would plummet on the descent. Which prompted Sean Kelly, Harmon's co-commentator, to reflect on the cycling gene.

These bike men were at their fittest now, he explained, but their immune systems would also be at their lowest after almost three hard weeks on the Tour.

"It's very difficult for the body to adapt to (the change in temperature) and yet they still, a big percentage of them, get through it without any problems and that's also, I suppose, part of the genes (they have). All the riders who have got here, they are something special, and not to pick up (some illness), in a situation like today where you get very warm and start sweating a lot on the climb itself, and then going downhill it gets so cold and, you know -- the body has to be really, really strong to be able to take all those conditions."

Kelly himself had a farmer's hardiness, if not a farmer's caution, for he famously in his heyday went down mountains like a bullet out of a gun. A viewer emailed in, asking about one particular day on the Tour back in the 1980s. Kelly and a team-mate had lost a lot of time on the climb up Col de Joux Plane but they went hell for leather on the descent into Morzine.

"The Joux Plane is a very fast descent and you can get up to 110 kilometres per hour quite easy, without taking major risks. But on the day of the descent we did take a lot of risks and it was pretty much (on) the limit on a lot of the corners."

David Harmon: "And what was the top speed you touched?"

Kelly: "124k."

Pause. Harmon: "124k an hour. That's frightening." No argument there: 124k is 77 miles per hour.

Weather conditions in the Pyrenees on Thursday were bad enough to keep the TV helicopters grounded. As the riders climbed Tourmalet, they entered the cloudline, becoming shrouded in the fog and rain.

The twisting road was thronged with fans on either side, leaving just a narrow tunnel for the racers. They had come to see the showdown between Alberto Contador, the defending champion, and his nearest rival Andy Schleck. Contador was in yellow, Schleck a mere eight seconds behind. Everyone knew the situation: Schleck, from Luxembourg, had to make time on Contador, the Spaniard, on this stage. He needed a 90-second cushion, at least, ahead of yesterday's time trial in Bordeaux. His attack would come on Tourmalet. The gradient was so steep here it was like cycling up a wall.

Schleck's team-mates put the hammer down in the foothills. One by one, they lined up for the ritual sacrifice, pounding out a few kilometres at the front until they were spent and discarded. By now a lot of riders had the thousand-yard stare, mouths wide open for the want of oxygen, pedalling in a trance of pain.

With 10km to the summit, Schleck attacked; Contador stayed on his wheel. "These," said Harmon, "are the only two men that matter now." Schleck kept pushing, Contador remained glued in his slipstream. Schleck repeatedly looked over his shoulder, staring at Contador, inviting him to take the lead. Verbals were exchanged too. They both knew the game -- the Spaniard wasn't buying.

With 4km left, Contador counter-attacked. Schleck responded and dug in behind. Then he pulled alongside, shoulder to shoulder. Schleck turned his head and glared at Contador. But he knew the champion had made a statement: Contador wasn't going to be burned off. "That was a big attack," said Kelly.

By now the sirens were roaring in their bodies: legs burning, hearts and lungs pumping at maximum capacity. The partisan supporters were maddened by the drama: a Schleck fan shouted obscenities at Contador, thrusting the Luxembourg flag in his face. The Spaniard calmly glared at him for a moment before facing the road again.

In the final kilometres they both turned the pedals as if cycling through melted tar. At the finish Contador allowed Schleck over the line first. He had the Tour -- the contender could have the stage. They climbed off their bikes and embraced, all smiles and mutual respect.